Generally, there are several designs of total ankle replacement prostheses. One type of total ankle replacement prostheses comprises a tibial implant with an elongated intramedullary stem. This type of prosthesis is exemplified by a total ankle replacement prostheses sold by Wright Medical Technology, Inc. (5677 Airline Road, Arlington, Tenn. 38002, USA) under the trademark INBONE Total Ankle System. In this system, the total ankle replacement prostheses is comprised of a tibial implant having an elongated intramedullary stem formed by a plurality of modular stem component pieces, a talar implant, and a polyethylene spacer.
Generally, this system has five sizes of implant sets that are employed as a function of the size of the ankle bones of a particular patient. Additionally, the tibial implant is constructed from different stem component pieces. The inferior part is a tibial tray. This has a set size and morphology specified by the size of the implant set chosen. Superior to this is a base, which also has a set size and morphology specified by the size of the implant set chosen. Superior to this are a variable number and size of stem component pieces that are chosen by the surgeon during the procedure to give the best fit in the tibial intramedullary canal. Furthermore, the talar implant has a set size and morphology specified by the size of the implant set chosen. There is a stem that fits into the inferior portion of the talar implant and extends inferiorly either 10 mm or 14 mm at a defined angle. The choice of which stem length to use is made by the surgeon during the procedure. Moreover, each implant set has a defined number of polyethylene spacers of varying height that fit into the tibial tray on the tibial implant. The height of the spacer to be used is chosen by the surgeon during the procedure, after the tibial and talar implant have been fit into the bones.
During the surgical procedure, the elongated intramedullary stem is constructed by coupling together the plurality of modular stem component pieces through an anterior ankle opening in a space formed between the lower end of the tibia and the upper end of the talus. This construction is performed after bone cuts have been made in those two bones, and the cut sections of bone have been removed to form the space. A second opening in the skin is made on the bottom of the heel, and a channel is drilled up through this skin incision, and then further up through the calcaneus and talus bones. That channel allows passage of instruments that aid in coupling the modular stem component pieces together to form the elongated intramedullary stem of the tibial prosthesis at a desired location in the tibia. The combination of these modular component pieces to form the tibial implant requires an intramedullary approach to the distal tibia.
There is a need to overcome the significant shortcomings in the removal of total ankle replacement prostheses such as the total ankle replacement prostheses delineated above during revision surgical procedures. In particular, there is a need to overcome the significant shortcomings in the removal of the elongated intramedullary stem of the tibial implant from the distal tibia during revision surgical procedures.
Of particular concern in the existing techniques for the removal of the tibial implant is the requirement for large bone windows to be cut into the lower end of the tibia to remove the elongated intramedullary stem component pieces of the tibial implant that have become fixed into the bone during the initial surgical procedures. The result of this bone destruction yields a tibia that makes further reconstructive procedures particularly problematic.
Accordingly, there is a particular need to overcome the significant shortcomings in the removal of the elongated intramedullary stem component pieces of the tibial implant from the distal tibia during revision surgical procedures.